Blended pressure-sensitive adhesives

ABSTRACT

A pressure-sensitive adhesive comprising a blend of at least two components, wherein the first component is at least one pressure-sensitive adhesive and second component is at least one thermoplastic material, wherein the components form a blended composition having more than one domain and, wherein one domain is substantially continuous (generally, the pressure-sensitive adhesive) and the other domain is substantially fibrillous to schistose (generally, the thermoplastic material). The second component can be (a) at least one thermoplastic elastomer, (b) at least one elastomer with a tackifying resin or (c) at least one elastomer.

RELATED APPLICATIONS

This application is the U.S. national stage of PCT/US96/13364. It is acontinuation-in-part of (1) application Ser. No. 08/577,603, filed Dec.22, 1995, now abandoned, which is incorporated herein by reference, and(2) application Ser. No. 08/578,010, filed Dec. 22, 1995, which isincorporated herein by reference, and which is a continuation-in-part ofapplication Ser. No. 08/390,780, filed Feb. 16, 1995, now abandoned.

TECHNICAL FIELD

This invention relates to pressure-sensitive adhesive compositions, and,more particularly, to pressure-sensitive adhesive compositions formedfrom at least two polymeric materials at least one of which is apressure-sensitive adhesive, and to methods of making blendedpressure-sensitive adhesives and to adhesive coated articles.

BACKGROUND OF THE INVENTION

There is an ongoing need to modify pressure-sensitive adhesives to meetthe needs of new applications. In general, when additives areincorporated into pressure-sensitive adhesives to modify theirproperties, care must be taken to avoid a loss in peel adhesion or shearstrength. This has prevented a wide use of thermoplastic materials asmodifiers.

Major classes of pressure-sensitive adhesives include tackified naturalrubbers; synthetic rubbers such as butyl rubber; and tackified linear,radial, star, and branched and tapered styrene block copolymers, such asstyrene-butadiene, styrene-ethylene/butylene and styrene-isoprene;polyurethanes; polyvinyl ethers; acrylics, especially those having longchain alkyl groups; poly-α-olefins; and silicones.

Generally, when additives are used to alter properties ofpressure-sensitive adhesives, the additives need to be miscible with thepressure-sensitive adhesive or to form homogeneous blends at themolecular level. Some types of pressure-sensitive adhesives have beenmodified with tackified thermoplastic elastomers, thermoplastics, andelastomers. For example, thermoplastic materials have been added topolymerized hot melt acrylic pressure-sensitive adhesives wherein thethermoplastic is a packaging material or recyclable tape backings. Inthese cases, the type and amount of thermoplastic material is controlledso that the thermoplastic material can function as a packaging materialwhile avoiding degradation of the adhesive properties of thepressure-sensitive adhesive.

However, more often than not when a non-tacky thermoplastic additive isblended with a pressure-sensitive adhesive, reduction of the overalladhesive properties of the blend (as compared to the pressure-sensitiveadhesive only) are observed. Thermoplastic polymers have been added tostyrene block copolymer adhesives to reduce the tack of the resultingpressure-sensitive adhesives for application of protective sheets tolarge area surfaces.

Pressure-sensitive adhesives, whether modified or not have been used formore than half a century for a variety of purposes. Generally,pressure-sensitive adhesives are used in tapes wherein a tape comprisesa backing, or substrate, and a pressure-sensitive adhesive. Typically, apressure-sensitive adhesive adheres with no more than applied fingerpressure and can be permanently tacky.

In the medical field, pressure-sensitive adhesive tapes are used formany different applications in the hospital and health areas. For mostapplications, tapes are applied directly to a patient's skin. It isimportant that the pressure-sensitive adhesive tape be compliant andnon-irritating to the skin, as well as adhering to the skin withoutcausing damage to the skin when the tape or adhesive coated article isremoved. A particularly useful medical application forpressure-sensitive adhesive tapes and articles is in the field oftransdermal patches. Such patches can be used as drug transportmembranes or to attach drug transport membranes to skin.

Although pressure-sensitive adhesive tapes and articles are widely usedin the medical field, pressure-sensitive adhesive tapes and articlesfind widespread use in many other applications. For example, transfertapes can be used to adhere two surfaces together such as the flaps ofpacking material or fabric to a surface. However, transfer tapeadhesives generally have little tensile strength and one solution hasbeen to add glass fibers to provide tensile strength.

Another use is in the field of labels, which require a large variety ofpressure-sensitive adhesives due to a wide variety of surfaces. However,the pressure-sensitive adhesives must be able to be cut easily withoutstringing out or oozing to permit efficient manufacturing processes.

Pressure-sensitive adhesives require a delicate balance of viscous andelastic properties that result in a four-fold balance of adhesion,cohesion, stretchiness and elasticity. Pressure-sensitive adhesivesgenerally comprise elastomers that are either inherently tacky, orelastomers or thermoplastic elastomers that are tackified with theaddition of tackifying resins.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a pressure-sensitiveadhesive comprising a blend of at least two components, wherein thefirst component is at least one pressure-sensitive adhesive and thesecond component is at least one thermoplastic material, wherein thecomponents form a blended composition having more than one domain and,wherein one domain is substantially continuous (generally, thepressure-sensitive adhesive) and the other domain is substantiallyfibrillous to schistose (generally, the thermoplastic material).

Alternatively, the second component can be (a) at least onethermoplastic elastomer, as described in Ser. No. 08/578,010, filed Dec.22, 1995 with a common assignee, (b) at least one elastomer with atackifying resin as described in Ser. No. 08/577,603, filed Dec. 22,1995 with a common assignee, or (c) at least one elastomer.

Advantageously, blended pressure-sensitive adhesives of the presentinvention provide adhesives having one or more of the followingproperties. These properties are improvements over a pressure-sensitiveadhesive prior to blending it with a thermoplastic material. Theseproperties include:

(1) a peel adhesion greater than and shear strength similar to that ofthe pressure-sensitive adhesive component if used alone,

(2) a shear strength greater than and peel adhesion similar to that ofthe pressure-sensitive adhesive component if used alone,

(3) an anisotropic peel adhesion,

(4) an anisotropic shear strength, and

(5) a tensile stress in the down-web direction that is at least 2 timesgreater than the tensile stress in the cross-web direction for allelongations up to the break elongation.

The pressure-sensitive adhesive component should be hot-melt processableand meet the Dahlquist criteria as described in Handbook ofPressure-sensitive Adhesive Technology, Edited by D. Satas, pg. 172,(1989) at use temperatures. Typically, the pressure-sensitive adhesivecomponent comprises 30-98 weight percent of the composition, preferably40-95 weight percent and more preferably 60-95 weight percent.Furthermore, the pressure-sensitive adhesive component could be a singlepressure-sensitive adhesive or the pressure-sensitive adhesive could bea mixture of several pressure-sensitive adhesives.

The thermoplastic material component is typically a high polymer thatcan soften when exposed to heat and can return to the solid state whencooled to room temperature. Useful thermoplastic materials are fiberformers and are essentially immiscible in the pressure-sensitiveadhesive component at use temperature, although the thermoplastic may bemiscible in the pressure-sensitive adhesive at processing temperatures.Typically, the thermoplastic material component comprises 2-70 weightpercent, preferably 5-60 weight percent and more preferably 5-40 weightpercent. Furthermore, the thermoplastic material component could be asingle thermoplastic material or the thermoplastic material could be amixture of several thermoplastic materials.

In another aspect, a melt process for blended pressure-sensitiveadhesives is described. Both components are melt mixed in a vessel andformed into a blended pressure-sensitive adhesive composition. Theforming step is either (1) extruding the melt blended components undershear and/or extensional flow conditions or (2) extruding and drawingthe melt blend. The formed composition is then cooled.

Also provided are pressure-sensitive adhesive coated tapes and articles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a stress-strain plot of the pressure-sensitive adhesive layerof Example 31 in both the down-web and cross-web directions.

FIG. 2 is the light scattering pattern for the pressure-sensitiveadhesive layer of Example 39 using the laser light scattering test.

FIG. 3 is a cross-sectional view in the down-web direction of thepressure-sensitive adhesive layer of Example 44 at 4000× using scanningelectron microscopy (SEM).

FIG. 4 is a cross-sectional view in the cross-web direction of thepressure-sensitive adhesive layer of Example 44 at 4000× using SEM.

FIG. 5 is the light scattering pattern for the pressure-sensitiveadhesive layer of Example 44 using the laser light scattering test.

FIG. 6 is a cross-sectional view in the down-web direction of thepressure-sensitive adhesive layer of Comparative Example C8, at 4000×using SEM.

FIG. 7 is the light scattering pattern for the pressure-sensitiveadhesive layer of Comparative Example C9, using the laser lightscattering test.

FIG. 8 is a cross-sectional view in the down-web direction of thepressure-sensitive adhesive layer of Example 46 at 4000× using SEM.

FIG. 9 is a cross-sectional view in the cross-web direction of thepressure-sensitive adhesive layer of Example 46 at 4000× using SEM.

FIG. 10 is the light scattering pattern for the pressure-sensitiveadhesive layer of Example 46 using the laser light scattering test.

FIG. 11 is a cross-sectional view of a transdermal matrix device of thepresent invention.

FIG. 12 is a cross-sectional view of a transdermal reservoir device ofthe present invention.

FIG. 13 is a cross-sectional view of a transdermal drug-in-adhesivedevice of the present invention.

FIG. 14 is a cross-sectional view of a transdermal multilaminate deviceof the present invention.

FIG. 15 is a cross-sectional view of an alternative embodiment of atransdermal multilaminate device of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The present invention provides a pressure-sensitive adhesive comprisinga blend of at least two components, wherein the first component is atleast one pressure-sensitive adhesive and the second component is atleast one thermoplastic material, wherein the components form a blendedcomposition having more than one domain. Alternatively, the secondcomponent can be (a) at least one thermoplastic elastomer, as describedin Ser. No. 08/578,010, filed Dec. 22, 1995 with a common assignee, (b)at least one elastomer with a tackifying resin as described in Ser. No.08/577,603, filed Dec. 22, 1995 with a common assignee, or (c) at leastone elastomer.

The pressure-sensitive adhesive component can be any material that haspressure-sensitive adhesive properties as described in The Handbook ofPressure-sensitive Adhesives, page 172, paragraph 1, 1989. Further,useful pressure-sensitive adhesives are hot-melt processable and meetthe Dahlquist criteria at use temperatures. Typically, thepressure-sensitive adhesive component comprises 30-98 weight percent,preferably 40-95 weight percent and more preferably 60-95 weightpercent. Furthermore, the pressure-sensitive adhesive component could bea single pressure-sensitive adhesive or the pressure-sensitive adhesivecould be a mixture of several pressure-sensitive adhesives.

Pressure-sensitive adhesives useful in the present invention includetackified natural rubbers, synthetic rubbers, tackified styrene blockcopolymers, polyvinyl ethers, acrylics, poly-α-olefins, and silicones.

Useful natural rubber pressure-sensitive adhesives generally containmasticated natural rubber, from 25 parts to 300 parts of one or moretackifying resins to 100 parts of natural rubber, and typically from 0.5to 2.0 parts of one or more antioxidants. Natural rubber may range ingrade from a light pale crepe grade to a darker ribbed smoked sheet andincludes such examples as CV-60, a controlled viscosity rubber grade andSMR-5, a ribbed smoked sheet rubber grade. Tackifying resins used withnatural rubbers generally include but are not limited to wood rosin andits hydrogenated derivatives; terpene resins of various softeningpoints, and petroleum-based resins, such as, the ESCOREZ™ 1300 series ofC5 aliphatic olefin-derived resins from Exxon. Antioxidants are used toretard the oxidative attack on natural rubber, which can result in lossof the cohesive strength of the natural rubber adhesive. Usefulantioxidants include but are not limited to amines, such as N-N′di-β-naphthyl-1,4-phenylenediamine, available as AgeRite D; phenolics,such as 2,5-di-(t-amyl)hydroquinone, available as Santovar AT™,available from Monsanto Chemical Co., tetrakis[methylene3-(3′,5′-di-tert-butyl-4′-hydroxyphenyl)propianate]methane, available asIRGANOX™ 1010 from Ciba-Geigy Corp., and2-2′-methylenebis(4-methyl-6-tert butyl phenol), available asAntioxidant 2246; and dithiocarbamates, such as zinc dithiodibutylcarbamate. Other materials can be added to natural rubber adhesives forspecial purposes, wherein the additions can include plasticizers,pigments, and curing agents to partially vulcanize thepressure-sensitive adhesive.

Another useful class of pressure-sensitive adhesives are thosecomprising synthetic rubber. Such adhesives are generally rubberyelastomers, which are either self-tacky or non tacky and requiretackifiers.

Self-tacky synthetic rubber pressure-sensitive adhesives include forexample, butyl rubber, a copolymer of isobutylene with less than 3percent isoprene, polyisobutylene, a homopolymer of isoprene,polybutadiene, or styrene/butadiene rubber. Butyl rubberpressure-sensitive adhesives often contain an antioxidant such as zincdibutyl dithiocarbamate. Polyisobutylene pressure-sensitive adhesives donot usually contain antioxidants. Synthetic rubber pressure-sensitiveadhesives, which generally require tackifiers, are also generally easierto melt process. They comprise polybutadiene or styrene/butadienerubber, from 10 parts to 200 parts of a tackifier, and generally from0.5 to 2.0 parts per 100 parts rubber of an antioxidant such as IRGANOX™1010. An example of a synthetic rubber is AMERIPOL™ 1011A, astyrene/butadiene rubber available from BF Goodrich. Tackifiers that areuseful include derivatives of rosins such as FORAL™ 85, a stabilizedrosin ester from Hercules, Inc., the SNOWTACK™ series of gum rosins fromTenneco, and the AQUATAC series of tall oil rosins from Sylvachem; andsynthetic hydrocarbon resins such as the PICCOLYTE™ A series,polyterpenes from Hercules, Inc., the ESCOREZ™ 1300 series of C5aliphatic olefin-derived resins and the ESCOREZ™ 2000 Series of C9aromatic/aliphatic olefin-derived resins. Other materials can be addedfor special purposes, including hydrogenated butyl rubber, pigments,plasticizers, liquid rubbers, such as VISTANEX™ LMMH polyisobutyleneliquid rubber available from Exxon, and curing agents to vulcanize theadhesive partially.

Styrene block copolymer pressure-sensitive adhesives generally compriseelastomers of the A—B or A—B—A type, where A represents a thermoplasticpolystyrene block and B represents a rubbery block of polyisoprene,polybutadiene, or poly(ethylene/butylene), and resins. Examples of thevarious block copolymers useful in block copolymer pressure-sensitiveadhesives include linear, radial, star and tapered styrene-isopreneblock copolymers such as KRATON™ D1107P, available from Shell ChemicalCo., and EUROPRENE™ SOL TE 9110, available from EniChem ElastomersAmericas, Inc.; linear styrene-(ethylene-butylene) block copolymers suchas KRATON™ G1657, available from Shell Chemical Co.; linearstyrene-(ethylene-propylene) block copolymers such as KRATON™ G1750X,available from Shell Chemical Co.; and linear, radial, and starstyrene-butadiene block copolymers such as KRATON™ D1118X, availablefrom Shell Chemical Co., and EUROPRENE™ SOL TE 6205, available fromEniChem Elastomers Americas, Inc. The polystyrene blocks tend to formdomains in the shape of spheroids, cylinders, or plates that causes theblock copolymer pressure-sensitive adhesives to have two phasestructures. Resins that associate with the rubber phase generallydevelop tack in the pressure-sensitive adhesive. Examples of rubberphase associating resins include aliphatic olefin-derived resins, suchas the ESCOREZ™ 1300 series and the WINGTACK™ series, available fromGoodyear; rosin esters, such as the FORAL™ series and the STAYBELITE™Ester 10, both available from Hercules, Inc.; hydrogenated hydrocarbons,such as the ESCOREZ™ 5000 series, available from Exxon; polyterpenes,such as the PICCOLYTE™ A series; and terpene phenolic resins derivedfrom petroleum or terpentine sources, such as PICCOFYN™ A100, availablefrom Hercules, Inc. Resins that associate with the thermoplastic phasetend to stiffen the pressure-sensitive adhesive. Thermoplastic phaseassociating resins include polyaromatics, such as the PICCO™ 6000 seriesof aromatic hydrocarbon resins, available from Hercules, Inc.;coumarone-indene resins, such as the CUMAR™ series, available fromNeville; and other high-solubility parameter resins derived from coaltar or petroleum and having softening points above about 85° C., such asthe AMOCO™ 18 series of alphamethyl styrene resins, available fromAmoco, PICCOVAR™ 130 alkyl aromatic polyindene resin, available fromHercules, Inc., and the PICCOTEX™ series of alphamethyl styrene/vinyltoluene resins, available from Hercules. Other materials can be addedfor special purposes, including rubber phase plasticizing hydrocarbonoils, such as, TUFFLO™ 6056, available from Lydondell Petrochemical Co.,Polybutene-8 from Chevron, KAYDOL™, available from Witco, and SHELLFLEX™371, available from Shell Chemical Co.; pigments; antioxidants, such asIRGANOX™ 1010 and IRGANOX™ 1076, both available from Ciba-Geigy Corp.,BUTAZATE™, available from Uniroyal Chemical Co., CYANOX™LDTP, availablefrom American Cyanamid, and BUTASAN™, available from Monsanto Co.;antiozonants, such as NBC, a nickel dibutyldithiocarbamate, availablefrom DuPont; liquid rubbers such as VISTANEX™ LMMH polyisobutylenerubber; and ultraviolet light inhibitors, such as IRGANOX™ 1010 andTINUVIN™ P, available from Ciba-Geigy Corp.

Polyvinyl ether pressure-sensitive adhesives are generally blends ofhomopolymers of vinyl methyl ether, vinyl ethyl ether or vinyl iso-butylether, or blends of homopolymers of vinyl ethers and copolymers of vinylethers and acrylates to achieve desired pressure-sensitive properties.Depending on the degree of polymerization, homopolymers may be viscousoils, tacky soft resins or rubber-like substances. Polyvinyl ethers usedas raw materials in polyvinyl ether adhesives include polymers based on:vinyl methyl ether such as LUTANOL™ M 40, available from BASF, andGANTREZ™ M 574 and GANTREZ™ M 555, available from ISP Technologies,Inc.; vinyl ethyl ether such as LUTANOL™A 25, LUTANOL™ A 50 and LUTANOL™A 100; vinyl isobutyl ether such as LUTANOL™ I 30, LUTANOL™ I 60,LUTANOL™ IC, LUTANOL™ I 60D and LUTANOL™ I 65D; methacrylate/vinylisobutyl ether/acrylic acid such as ACRONAL™ 550 D, available from BASF.Antioxidants useful to stabilize the polyvinylether pressure-sensitiveadhesive include, for example, IONOX™ 30 available from Shell, IRGANOX™1010 available from Ciba-Geigy, and Antioxidant ZKF available from BayerLeverkusen. Other materials can be added for special purposes asdescribed in BASF literature including tackifier, plasticizer andpigments.

Acrylic pressure-sensitive adhesives generally have a glass transitiontemperature of about −20° C. or less and may comprise from 100 to 80weight percent of a C₃-C₁₂ alkyl ester component such as, for example,isooctyl acrylate, 2-ethyl-hexyl acrylate and n-butyl acrylate and from0 to 20 weight percent of a polar component such as, for example,acrylic acid, methacrylic acid, ethylene vinyl acetate, N-vinylpyrrolidone and styrene macromer. Preferably, the acrylicpressure-sensitive adhesives comprise from 0 to 20 weight percent ofacrylic acid and from 100 to 80 weight percent of isooctyl acrylate. Theacrylic pressure-sensitive adhesives may be self-tacky or tackified.Useful tackifiers for acrylics are rosin esters such as FORAL™ 85,available from Hercules, Inc., aromatic resins such as PICCOTEX™LC-55WK, aliphatic resins such as PICCOTAC™ 95, available from Hercules,Inc., and terpene resins such as α-pinene and β-pinene, available asPICCOLYTE™ A-115, and ZONAREZ™ B-100 from Arizona Chemical Co. Othermaterials can be added for special purposes, including hydrogenatedbutyl rubber, pigments, and curing agents to vulcanize the adhesivepartially.

Poly-α-olefin pressure-sensitive adhesives, also called a poly(1-alkene)pressure-sensitive adhesives, generally comprise either a substantiallyuncrosslinked polymer or a uncrosslinked polymer that may have radiationactivatable functional groups grafted thereon as described in U.S. Pat.No. 5,209,971 (Babu, et al) which is incorporated herein by reference.The poly-α-olefin polymer may be self tacky and/or include one or moretackifying materials. If uncrosslinked, the inherent viscosity of thepolymer is generally between about 0.7 and 5.0 dL/g as measured by ASTMD 2857-93, “Standard Practice for Dilute Solution Viscosity ofPolymers”. In addition, the polymer generally is predominantlyamorphous. Useful poly-α-olefin polymers include, for example, C₃-C₁₈poly(1-alkene) polymers, preferably C₅-C₁₂ α-olefins and copolymers ofthose with C₃ and more preferably C₆-C₈ and copolymers of those with C₃.Tackifying materials are typically resins that are miscible in thepoly-α-olefin polymer. The total amount of tackifying resin in thepoly-α-olefin polymer ranges between 0 to 150 parts by weight per 100parts of the poly-α-olefin polymer depending on the specificapplication. Useful tackifying resins include resins derived bypolymerization of C₅ to C₉ unsaturated hydrocarbon monomers,polyterpenes, synthetic polyterpenes and the like. Examples of suchcommercially available resins based on a C₅ olefin fraction of this typeare WINGTACK™ 95 and WINGTACK™ 115 tackifying resins available fromGoodyear Tire and Rubber Co. Other hydrocarbon resins include REGALREZ™1078 and REGALREZ™ 1126 available from Hercules Chemical Co., and ARKON™P115 available from Arakawa Chemical Co. Other materials can be addedfor special purposes, including antioxidants, fillers, pigments, andradiation activated crosslinking agents.

Silicone pressure-sensitive adhesives comprise two major components, apolymer or gum, and a tackifying resin. The polymer is typically a highmolecular weight polydimethylsiloxane or polydimethyldiphenylsiloxane,that contains residual silanol functionality (SiOH) on the ends of thepolymer chain, or a block copolymer comprising polydiorganosiloxane softsegments and urea terminated hard segments. The tackifying resin isgenerally a three-dimensional silicate structure that is endcapped withtrimethylsiloxy groups (OSiMe₃) and also contains some residual silanolfunctionality. Examples of tackifying resins include SR 545, fromGeneral Electric Co., Silicone Resins Division, Waterford, N.Y., andMQD-32-2 from Shin-Etsu Silicones of America, Inc., Torrance, Calif.Manufacture of typical silicone pressure-sensitive adhesives isdescribed in U.S. Pat. No. 2,736,721(Dexter). Manufacture of siliconeurea block copolymer pressure-sensitive adhesive is described in U.S.Pat. No. 5,214,119(Leir, et al). Other materials can be added forspecial purposes, including, pigments, plasticizers, and fillers.Fillers are typically used in amounts from 0 parts to 10 parts per 100parts of silicone pressure-sensitive adhesive. Examples of fillers thatcan be used include zinc oxide, silica, carbon black, pigments, metalpowders and calcium carbonate.

The second component of the pressure-sensitive adhesive composition ofthe present invention is a thermoplastic material or alternatively aseither (a) a thermoplastic elastomeric material, (b) an elastomericmaterial with a tackifying resin, as previously described, or (c) anelastomeric material. The thermoplastic material component is typicallya high polymer that can soften when exposed to heat and can return tothe solid state when cooled to room temperature. Useful thermoplasticmaterials are fiber formers and are essentially immiscible in thepressure-sensitive adhesive component at the use temperature, althoughthe thermoplastic may be miscible in the pressure-sensitive adhesive atmelt processing temperatures. Typically, the thermoplastic materialcomponent comprises 2-70 weight percent at the pressure-sensitiveadhesive composition, preferably 5-60 weight percent and more preferably5-40 weight percent. Furthermore, the thermoplastic material componentcould be a single thermoplastic material or a mixture of severalthermoplastic materials.

Thermoplastic materials useful in the present invention include, forexample, polyolefins such as isotactic polypropylene, low density orlinear low density polyethylene, medium density polyethylene, highdensity polyethylene, polybutylene, polyolefin copolymers orterpolymers, such as ethylene/propylene copolymer and blends thereof;ethylene-vinyl acetate copolymers such as ELVAX™ 260, available fromDuPont Chemical Co., ethylene acrylic acid copolymers, ethylenemethacrylic acid copolymers such as SURLYN™1702, available from DuPontChemical Co., polymethylmethacrylate, polystyrene, ethylene vinylalcohol, polyester, amorphous polyester, polyamides, fluorinatedthermoplastics, such a polyvinylidene fluoride, polytetrafluoroethylene,fluorinated ethylene/propylene copolymers and fluorinatedethylene/propylene copolymers and halogenated thermoplastics, such as achlorinated polyethylene. Any single thermoplastic can be blended withat least one pressure-sensitive adhesive. Alternatively, a blend ofthermoplastic materials may be used, provided the resultant blend whenmelt mixed with at least one pressure-sensitive adhesive produces atleast two distinct domains at the use temperature.

Thermoplastic elastomeric materials are typically materials that form atleast two phases at 21° C., flow at a temperature greater than 50° C.and exhibit elastomeric properties. Thermoplastic elastomeric materialsthat are useful are further described in Ser. No. 08/578,010, filed Dec.22, 1995 with a common assignee.

Elastomeric materials are typically materials that form one phase at 21°C., have a glass transition temperature less than about 0° C. andexhibit elastomeric properties. Tackifying resins may be added tofacilitate blending of the pressure-sensitive component with theelastomeric material component. Elastomeric materials that are usefulare further described in Ser. No. 08/577,603, filed Dec. 22, 1995 with acommon assignee.

Preferably, each of the components has similar melt viscosity. Theability to form a finely dispersed morphology is related to a ratio ofthe shear viscosity of the components at melt mixing temperatures. Shearviscosity is determined using capillary rheometry at a shear rateapproximating extrusion blending conditions, that is, 100s⁻¹ and 175° C.When a higher viscosity component is present as the minor component, theviscosity ratio of minor to major components is preferably less thanabout 20:1, more preferably less than about 10:1. When a lower viscositymaterial is present as the minor component, the viscosity ratio of minorto major components are preferably greater than about 1:20, morepreferably greater than about 1:10. The melt viscosities of individualcomponents may be altered by the addition of plasticizers tackifiers orsolvents or by varying mixing temperatures.

It is also preferable that at least one of the components be easilyextended during melt blending and coating operations to form a finelydispersed morphology with domains that are fibrillose to schistose, forexample, forming sheets, ribbons, fibers, ellipsoids or the like,oriented in the down-web direction in the substantially continuous orco-continuous domain of the other polymeric material. Sufficientinterfacial adhesion between the pressure-sensitive adhesive componentand the thermoplastic material component preferably exists to withstandthe shear and extensional deformation present during the forming stepand to promote formation of a continuous film.

If none of the polymeric materials can be sufficiently dispersed duringthe melt blending, a pressure-sensitive adhesive coating may be producedthat has gross discontinuities and is grainy in texture. Through use ofsuitably selected conditions of mixing, melt viscosity ratios, andshear/stretch conditions during extrusion, the thickness of thefibrillose to schistose domains can be made sufficiently thin thatcatastrophic delamination from the substantially continuous orco-continuous domain will not occur. Preferably, the thickness of thefibrillose to schistose domains is less than about 20 micrometers, morepreferably less than about 10 micrometers, and most preferably less thanabout 1 micrometers.

In the present invention, the components are blended and coated usingmelt extrusion techniques. Mixing can be done by any method that resultsin a substantially homogeneous distribution of the components. The blendof components is prepared by melt mixing the components in the molten orsoftened state using devices that provide dispersive mixing,distributive mixing, or a combination of dispersive and distributivemixing. Both batch and continuous methods of blending may be used.Examples of batch methods include BRABENDER™ or BANBURY™ internalmixing, and roll milling. Examples of continuous methods include singlescrew extruding, twin screw extruding, disk extruding, reciprocatingsingle screw extruding, and pin barrel single screw extruding.Continuous methods can include both distributive elements, pin mixingelements, and static mixing elements, and dispersive elements such asMaddock mixing elements or Saxton mixing elements.

After the mixing step, the softened or molten blend is formed into acoating of a blended pressure-sensitive adhesive that has a distinctivemorphology. In the present invention the pressure-sensitive adhesivecomponent forms a substantially continuous domain, while thethermoplastic material component forms a discontinuous domain that isfibrillose to schistose in nature by processes that involve either shearor extensional deformations or both.

Continuous forming methods include drawing the pressure-sensitiveadhesive composition out of a film die and subsequently contacting amoving plastic web or other suitable substrate. A related continuousmethod involves extruding the pressure-sensitive adhesive compositionand a coextruded backing material from a film die and subsequentlycooling to form a pressure-sensitive adhesive tape. Other continuousforming methods involve directly contacting the pressure-sensitiveadhesive blend to a rapidly moving plastic web or other suitablesubstrate. In this method, the pressure-sensitive adhesive blend can beapplied to the moving web using a die having flexible die lips such as areverse orifice coating die and other contact dies using rotating rods.After forming, the pressure-sensitive adhesive coatings are solidifiedby quenching using both direct methods, such as chill rolls or waterbaths, and indirect methods, such as air or gas impingement.

Either prior to or after a pressure-sensitive adhesive is coated onto abacking, the pressure-sensitive adhesive compositions of the inventionmay be cross-linked by treatment with radiation. Suitable radiationsources include ultraviolet and electron beam. When ultravioletirradiation is used, photoinitiators are generally added to the adhesiveblend. If present such photoinitiators are those that are known to thoseskilled in the article as being compatible or useful with specificpressure-sensitive adhesives.

Advantageously, blended pressure-sensitive adhesives of the presentinvention provide adhesives having one or more of the followingproperties. These properties are improvements over a pressure-sensitiveadhesive prior to blended it with a thermoplastic material. Theseproperties include:

(1) a peel adhesion greater than and shear strength similar to that ofthe pressure-sensitive adhesive component if used alone,

(2) a shear strength greater than and peel adhesion similar to that ofthe pressure-sensitive adhesive component if used alone,

(3) an anisotropic peel adhesion,

(4) an anisotropic shear strength, and

(5) a tensile stress in the down-web direction that is at least twotimes greater than the tensile stress in the cross-web direction for allelongations up to the break elongation.

Enhanced peel adhesions have been observed that are from 20% to 200%greater than those seen with the pressure-sensitive adhesive componentalone without substantial decreases in shear strength. This appears tobe due to the additional energy dissipation caused by limitedinterfacial delamination or void formation between the domains duringpeel. This is observed when the discontinuous domain is thethermoplastic material component. This will also depend on the type andamount of the component used. Generally enhanced peel adhesions occursover a range of 5% to 20% thermoplastic component. For example, if anacrylic pressure-sensitive adhesive is used, thermoplastic materialcomponents that do not exhibit enhanced peel adhesion include, forexample, polystyrene, polymethylmethacrylate and amorphous polyester.Likewise, thermoplastic materials that do exhibit enhanced peel adhesioninclude for example, linear low-density polyethylene. low-densitypolyethylene, and ethylene vinylacetate.

Shear strength, as measured by holding time, have been observed that arefrom 25% to 200% greater than those seen with the pressure-sensitiveadhesive component alone without substantial decreases in peel adhesion.This appears to be due to the reinforcing nature of the thermoplasticmaterial domains and has been observed over a range of thermoplasticmaterial of 5% to 25%. Thermoplastic material types do not seem to be acontrolling factor.

The anisotropic peel force is an unusual property wherein the forcenecessary to peel the PSA article from a surface to which it is adheredvaries when measured along different axes. That is, the PSA articledisplays different adhesion when peeled from the surface in differentdirections. When a pressure-sensitive article is made by extruding theadhesive, the preferred orientation of the elastomer will generally bethe “down-web direction” (or “DW”), that is, parallel to the extrusioncoating line. The direction perpendicular to the extrusion coating lineis generally referred to as the “cross-web direction” (or “CW”).Generally, the peel force in the parallel direction will be less than90%, preferably less than 50%, and most preferably less than 10%, of thehigher peel force (i.e., the peel force in the perpendicular direction).This effect is due to the down-web oriented fibrillous to schistosemorphology of the discontinuous phase. When thermoplastic materials havea higher tensile strength, i.e., polystyrene, polymethylmethacrylate,amorphous polyester, and high density polyethylene, anisotropic peelsare observed when the range of thermoplastic material is between 5 to20%. When the thermoplastic material has a lower tensile strength, i.e.,linear low density polyethylene, low density polyethylene, and ethylenevinyl acetate, the range is from 20% to 40%. It is believed that theanisotrdpic peel adhesion is due to the stiffening of the PSAcomposition by the thermoplastic material in the down-web direction.

Anisotropic shear strength is often observed when a pressure-sensitiveadhesive of the invention exhibits anisotropic peel adhesion. In suchcases, the direction of higher shear strength usually corresponds to thedirection of lower peel adhesion. However, anisotropic shear strengthcan occur without the occurrence of a corresponding anisotropic peeladhesion. The shear strength in the low shear direction will be lessthan 80%, preferably less than 50%, and most preferably less than 10%,of the higher shear strength.

A tensile stress in the down-web direction has been observed that is atleast two-times greater than the tensile stress in the cross-webdirection for all elongations up to the break elongation. The tensilestress is influenced by the type of materials selected, theirconcentrations, the length to diameter ratio of the discontinuousdomains and the break elongation of the thermoplastic materialcomponent. Tensile stresses have been observed ranging from 0.69 to 20.7MPa (100 to 3000 psi) with constructions of the invention. By formingthe fiber-like to schistose-like discontinuous domains in situ, finerthermoplastic fibrillous to schistose domains (less than 1 μm) can beformed compared to pressure-sensitive adhesive constructions composed ofglass fiber placed in the pressure-sensitive adhesive. Generally, highertensile stress properties are obtained with stiffer thermoplasticmaterials, such as polystyrene, polymethylmethacrylate, amorphouspolyester and high density polyethylene. High down-web tensile stressesand smaller break elongations also afford pressure-sensitive adhesivecompositions of the invention to have better dispensing properties whenused, for example, as transfer adhesive tapes.

The compositions of the present invention, depending on specificformulation, can be used to make various pressure-sensitive articlesutilizing the anisotropic properties of some formulations,pressure-sensitive adhesive tapes, pressure-sensitive adhesive transfertapes, pressure-sensitive adhesive medical tapes, including for exampletransdermal drug delivering devices, or pressure-sensitive adhesivecoatings directly onto desired articles. Alternatively, the variouspressure-sensitive articles can utilize pressure-sensitive adhesivecompositions comprising at least one pressure-sensitive adhesivecomponent and at least one polymeric component that can be either (a) athermoplastic elastomeric material, (b) an elastomeric material with atackifying resin, as previously described, or (c) an elastomericmaterial without a tackifying resin.

The compositions of the present invention are also useful in medicalapplications including transdermal drug delivery devices. Such devicesgenerally involve a controlled adhesion to skin. The adhesion should beenough for the application to stick initially and not increase over timeto a point where skin may be damaged upon removal or decrease over timeto a point where the devices may fall off the skin surface. Transdermaldrug delivery devices are designed to deliver a therapeuticallyeffective amount of drug through or to the skin of a patient.Transdermal drug delivery provides significant advantages; unlikeinjection, it is noninvasive; unlike oral administration, it avoidshepatic first pass metabolism, it minimizes gastrointestinal effects,and it provides stable blood levels.

A variety of transdermal drug delivery devices are known. Devices knownto the art include matrices whereby the drug is placed within anon-adhesive polymeric material; reservoir devices in which the drug isplaced in a liquid and delivered to the skin through a rate controllingmembrane; drug-in-adhesive devices whereby the drug is placed within anadhesive polymer; and more complex multilaminate devices involvingseveral distinct layers, e.g. layers for containing drug, for containingexcipients, for controlling the rate of release of the drug andexcipients, and for attaching the device to the skin.

All of the devices incorporate a drug formulation, an adhesive tomaintain contact with the patient's skin, a release liner that protectsthe device during storage (and that is removed prior to the applicationof the device to the skin), and a backing that protects the device fromexternal contamination while in use.

A matrix device is shown in FIG. 11. Device 10 comprises a backing 12, amatrix 14 containing the drug and optionally excipients, a concentricadhesive layer 16 surrounding the matrix 14, and a release liner 18.

A reservoir device is shown in FIG. 12. Device 20 comprises a backing22, a liquid formulation 24 containing the drug and optionallyexcipients, a membrane 25 for controlling the rate at which the drug andexcipients are delivered to the skin, an adhesive layer 26, and arelease liner 28. The adhesive layer may also be present as a concentricring as depicted in connection with the matrix device (FIG. 11).

A drug-in-adhesive device is shown in FIG. 13. Device 30 comprises abacking 32, an adhesive layer 37 containing drug and optionallyexcipients, and a release liner 38.

A multilaminate device is shown in FIG. 14. Device 40 comprises abacking 42, an adhesive layer 47 containing drug and optionallyexcipients, a second adhesive layer 43 that controls the rate at whichthe drug and excipients are delivered to the skin, and a release liner48.

A second embodiment of a multilaminate device is shown in FIG. 15.Device 50 comprises a backing 52, an adhesive layer 57 containing drugand optionally excipients, a membrane 55, a second adhesive layer 56,and a release liner 58. The membrane may be selected to control the rateat which the drug and excipients are delivered to the skin or to providephysical stability to the device.

Skin adhesion is a critical requirement of any transdermal drug deliverysystem. Because drug delivery is directly proportional to the skincontact area, the device must establish and maintain sufficient skinadhesion until it is removed. Adhesives that are used in skin contactinglayers will preferably exhibit the following properties: good initialskin adhesion, that is, tack; adequate adhesion during the wear period;clean release from the skin; and skin compatibility (nonirritating andnonsensitizing). It is important that these properties be maintainedwhen the adhesive is exposed to the particular drug and excipients beingused in a given device.

Adhesives used in layers that either contain drug and excipients orthrough which drug and excipients pass must also be compatible with thedrug and excipients. Preferably the adhesives will not react chemicallywith the drug or excipients. In many instances, it is also preferablethat the drug be dissolved in the adhesive rather than dispersed in it.It will often be desirable or even necessary to customize the adhesivefor a particular drug/excipient combination.

The transdermal delivery devices can be made in the form of an articlesuch as a tape, a patch, a sheet, a dressing or any other form known tothose skilled in the art. Generally the device will be in the form of apatch of a size suitable to deliver a preselected amount of the drug.Suitable release liners include those enumerated above in connectionwith the preparation of PSA tapes.

Anisotropic peel adhesion property enables pressure-sensitive adhesivearticles of the invention (e.g., pressure-sensitive adhesive-coatedtapes or sheets) to be advantageously used in graphic arts applications,(e.g., a premask tape, a prespace tape, a graphic art film, die-cutproducts, or dry transfer lettering, such as the graphic arts productsdescribed by Satas, supra, Chap. 32). The anisotropic PSA articles ofthis invention can also be used as a diaper fastening tape, a walldecoration film, or other constructions wherein differential peel isdesirable.

As mentioned above, in one embodiment of the pressure-sensitive adhesivearticle of this invention, the type and concentration of thepressure-sensitive adhesive and thermoplastic material components aresufficient to impart anisotropic peel force to the article. An articlehaving anisotropic peel force may be used as a graphics application tape(including both premask and prespace tapes), which is useful in graphicarts work. For example, die-cut graphics often take the form of suchvinyl decals. Typically, the decal is formed by cutting it from a sheetof colored, adhesive-coated vinyl film which has been laminated to arelease liner. The waste or weed is peeled away and then a graphicsapplication tape is applied to the top of the die-cut decals to liftthem from the release liner while keeping them in register. The decalsare then transferred to the desired target substrate and the graphicsapplication tape is peeled away. Such graphics application tapes need tobe aggressive enough to reliably lift all of the components of thegraphic (i.e., the decals in this example) from the release liner, butstill should be easily removed after transferring the graphic to thetarget substrate and should not pull any of the graphic off the target.This is often a difficult balance to achieve. Using thepressure-sensitive adhesive tape of the present invention as thegraphics application tape, one could pull in the high adhesion directionto remove the graphic from the liner, apply it to the target substrate,and then remove the graphics application tape by pulling in the lowadhesion direction. Other graphics application tapes do not involvedie-cut components but there would still be an advantage to havinggraphics application tapes with a very easy removal direction becausethe graphics can be very wide and difficult to pull off withconventional adhesives. When a conventional adhesive is formulated tohave a low removal force, the ability to hold onto the graphic isimpaired. The anisotropic pressure-sensitive adhesive tapes of thepresent invention can have high holding ability but still have a lowremoval force.

Another application for an anisotropic pressure-sensitive adhesivearticle of this invention is as a large area graphic or protective filmthat aggressively adheres to a surface that it is applied to but can bereadily removed. Some useages of this article include, an advertisinggraphic on the side of a truck, a protective film for vehicle finishesduring manufacture, transportation, storage, and a protective film formicroreplicated surfaces used in graphic displays on optical screens.

Another application in which the anisotropic peeling properties of theinvention can be used is in the manufacture of diaper fastening tape.The low peel force of such a tape in the machine direction would allow alarge stock roll of the tape to be unwound for converting without theaid of a release material. In the process of converting the stock rollto individual tapes, the tape could be cut so the cross direction of thestock roll, which is the high adhesion direction, becomes the directionof peel on the finished diaper product.

Yet another application of the pressure-sensitive adhesive article wouldbe in wall decoration films. One can produce a graphic wall decorationwith the anisotropic pressure-sensitive adhesive article in such a waythat the high adhesion direction is vertical or down the wall to preventfailure due to gravity, while the low adhesion direction is horizontalto provide an easy removal direction avoiding any damage to the wall.

Another use for an anisotropic pressure-sensitive adhesive article ofthe invention is in masking applications that use a maskant sheet ordrape adhesively fixed to a substrate in order to mask a large area ofthe substrate. Maskant sheets or drapes are used in automotive paintingor refinishing and in commercial and residential wall painting wherein apaper or plastic film is taped to the autobody part or the wall in orderto prevent overspraying of a coating onto the area that is masked. Ifthe maskant sheet is relatively long and heavy it will induce a constantpeel force in the direction of the drape that may cause the tape to pullaway from the substrate. The adhesive can be formulated to be moreaggressive and overcome the stress induced by the weight of the drape,but the tape may then be difficult to remove completely from thesubstrate after the painting operation is completed. An anisotropicpressure-sensitive adhesive tape of the present invention that exhibitslow peel force in the machine direction and high peel force in the crossdirection is useful in such masking applications. The tape can be madeto have high peel resistance or holding ability in the cross directionto overcome the peel stress induced by the weight of the drape, but haveonly a very low peel or removal force in the lengthwise direction toremove the tape without damage to the substrate.

Pressure-sensitive adhesive articles are made by applying thepressure-sensitive adhesive by well known hot melt coating processes.Any suitable substrates that can by used, including, but not limited to,for example, cloth and fiber-glass cloth, metallized films and foils,polymeric films, nonwovens, paper and polymer coated paper, and foambackings. Polymer films include, but are not limited by, polyolefinssuch as polypropylene, polyethylene, low density polyethylene, linearlow density polyethylene and high density polyethylene; polyesters suchas polyethylene terephthalate; polycarbonates; cellulose acetates;polyimides such as KAPTON™. Nonwovens, generally made from randomlyoriented fibers, include, but are not limited by, nylon, polypropylene,ethylene-vinyl acetate copolymer, polyurethane, rayon and the like. Foambackings include, but are not limited by acrylic, silicone,polyurethane, polyethylene, neoprene rubber, and polypropylene, and maybe filled or unfilled. Backings that are layered, such aspolyethylene-aluminum membrane composites, are also suitable.

In the case of pressure-sensitive tapes, these materials are typicallyapplied by first making a tape construction which comprises a layer ofthe pressure-sensitive adhesive material coated on a backing. Theexposed surface of the PSA coating may be subsequently applied to asurface from which it could be released later or directly to the desiredsubstrate.

A transfer adhesive tape can be made by coating the composition betweentwo liners both of which are coated with a release coating. The releaseliners often comprise a clear polymeric material such as polyolefin orpolyester that is transparent to ultraviolet radiation. Preferably, eachrelease liner is first coated with a release material for thepressure-sensitive adhesive utilized in the invention.

This invention is further illustrated by the following examples whichare not intended to limit the scope of the invention. The following testmethods were used to evaluate and characterize film surfaces produced inthe examples.

EXAMPLES

This invention is further illustrated by the following examples whichare not intended to limit the scope of the invention. In the examples,all parts, ratios and percentages are by weight unless otherwiseindicated. The following test methods were used to characterize thepressure-sensitive adhesive compositions in the following examples:

Test Methods

Shear Viscosity

Shear viscosity was determined using a high pressure capillary rheometer(RHEOGRAPH 2001, available from Gottfert Co.) operated with a capillarydie 30 mm long and 1 mm in diameter at a temperature of 175° C. unlessotherwise noted. At a 100 s⁻¹ shear rate, the apparent viscosity wascalculated from Poiseuille's equation and converted to true viscosityusing the Weissenberg-Rabinovitch correction.

180° Peel Adhesion Test

Pressure-sensitive adhesive tape samples 1.25 cm wide and 15 cm longwere tested for 180° peel adhesion to glass and/or smooth cast biaxiallyoriented polypropylene films. The samples were adhered to the testsurfaces by rolling the tapes with a 2.1 kg (4.5 lb.) roller using 4passes. After aging at controlled temperature and humidity conditions(approximately 22° C., 40% relative humidity) for approximately 1 hour,the tapes were tested using a Model 3M90 slip/peel tester, availablefrom Instrumentors, Inc., in 180° geometry at 30.5 cm/min (12 in/min)peel rate, unless otherwise noted.

Shear Strength Test

Shear strength, as determined by holding time, was measured onpressure-sensitive adhesive tape samples at controlled temperature andhumidity conditions (approximately 22° C., 40% relative humidity). A25.4 mm×25.4 mm (1.0 in×1.0 in) section of the tape was adhered to astainless steel sheet with a 2.1 kg (4.5 lb.) roller using 4 passes. A1000 gram weight was hung from to the sample. The amount of time for theweight to drop was recorded. The test was stopped at 10,000 minutes.

Laser Light Scattering Test

Pressure-sensitive adhesive tape samples were tested for their lightscattering characteristics. A helium neon laser operating at 632 nmwavelength and 3 mm spot size was directed normal to the plane of theadhesive tape. A shutter controlled the exposure time of the beam on thesample and the resulting light-scattering image was captured on Polaroid#55 film that was 120 mm behind the tape sample. The presence of theoriented fibrillous to schistose domains resulted in a smearing of thescattered light intensity into a fine or broad line oriented at 90degrees from the fiber or down-web direction in the plane of the film.The absence of the dispersed domain or the presence of a sphericallyshaped dispersed domain resulted in a spherical or isotropic lightscattering pattern.

Tensile Test

The tensile test was used to obtain stress-strain data for the variousblended pressure-sensitive adhesive coatings. 2.54 cm (1.0 in) widesamples having thicknesses of 51 to 127 microns (2-5 mils) were testedusing an INSTRON™ Model 1122 equipped with an INSTRON™ Series 9 softwarepackage at a cross-head speed of 102 cm/min (40 in/min). Samples weretested in both DW and CW directions.

Skin Adhesion Test

Skin adhesion testing was carried out by placing tape samples 2.5 cmwide by 5 cm long on the back of a human subject. Each tape was rolleddown with one forward and one reverse pass using a 2 kg roller moved ata rate of about 30 cm/min. Adhesion to the skin was measured as the peelforce required to remove the tape at 180° angle at a 15 cm/min rate ofremoval. Adhesion was measured immediately after initial application(T₀) and after 48 hours (T₄₈). Preferred skin adhesive generallyexhibits a T₀ of between about 50 to 100 grams (1.9 to 3.8 N/dm) and aT₄₈ of between about 150 to 300 grams (5.8 to 11.5 N/dm). Results of 14tests were averaged.

Skin Adhesion Lift Test

When the 48 hour skin adhesion test was performed, the tape sample wasexamined for the amount of area that was lifted (released) from the skinprior to removal of the tape and ratings were given as:

0 no visible lift

1 lift only at edges of tape

2 lift over 1% to 25% of test area

3 lift over 25% to 50% of test area

4 lift over 50% to 75% of test area

5 lift over 75% to 100% of test area

Results of 14 tests were averaged. Preferred skin adhesives willgenerally exhibit an average rating below about 2.5.

Skin Adhesive Residue Test

When the 48 hour skin adhesion test was performed, the skin underlyingthe tape sample was visually inspected to determine the amount ofadhesive residue on the skin surface and was rated as:

0 no visible residue

1 residue only at edges of tape

2 residue covering 1% to 25% of test area

3 residue covering 25% to 50% of test area

4 residue covering 50% to 75% of test area

5 residue covering 75% to 500% of test area

Results of 14 tests were averaged. Preferred skin adhesives willgenerally exhibit an average rating below about 2.5.

Examples 1-17 and Comparative Examples C1

In Examples 1 and 2 a pressure-sensitive adhesive, acrylic component (95weight percent isooctyl acrylate/5 weight percent acrylic acid, wateremulsion polymerized, shear viscosity—150 Pa-s, prepared according toU.S. Pat. No. RE 24,906, (Ulrich) that is incorporated herein byreference, and dried), and a thermoplastic material component, ELVAX™210 (ethylene vinyl-acetate copolymer, shear viscosity 10 Pa-s,available from Dupont), were melt-blended in a 34 mm diameter fullyintermeshing co-rotating twin-screw extruder (LEISTRITZ™ Model LSM34GL,available from Leistritz, Inc.). The thermoplastic material componentwas introduced into the feed throat of the extruder and thepressure-sensitive adhesive component was introduced in zone 4. Thetemperature was progressively increased from 38° C. to 177° C. (100° F.to 350° F.) from zone 1 to zone 4. The temperature of the remainingzones was maintained at 177° C. to 191° C. (350° F. to 375° F.). InExamples 1 and 2 the feed rates were adjusted to provide a ratio ofpressure-sensitive adhesive component to thermoplastic materialcomponent of 95:5 and 85:15, respectively.

The twin-screw extruder was continuously discharged at a pressure of atleast about 0.69 MPa (100 psi) into a 25.4 cm (10 inch) wide film die(ULTRAFLEX™ 40 die, Model 89-12939, available from Extrusion Dies,Inc.). The die was maintained at 177° C. to 191° C. (350° F. to 375° F.)and the die gap was 0.5 to 0.8 mm (20 to 30 mils). The blended adhesivecomposition was fed between a 51 μm (2 mil) thick biaxially orientedpolyethylene terephthalate film and a release coated paper web at a rateof 6.4 kg/hr (14 lbs/hr). The film and the web were fed at a rate of13.7 m/min (45 fpm) between chill rolls maintained at a temperature of21° C. (70° F.) to form a pressure-sensitive adhesive tape with apressure-sensitive adhesive composition layer thickness of about 64microns (2.5 mils). Alternatively, some blended adhesive composition wasfed between two release coated paper webs for further testing of theadhesive layer or subsequent transfer of the adhesive layer to adifferent substrate.

Examples 3, 4 and 5 were prepared in the same manner as Example 1 exceptthat a different thermoplastic material component, ELVAX™ 240 (ethylenevinyl-acetate copolymer, shear viscosity—210 Pa-s), was added to thepressure-sensitive adhesive component at ratios of pressure-sensitiveadhesive component to thermoplastic material component of 95:5, 85:15and 70:30, respectively. Examples 6, 7 and 8 were prepared in the samemanner as Examples 3, 4 and 5 respectively, except that a differentthermoplastic material component, ELVAX™ 450 (ethylene vinyl-acetatecopolymer, shear viscosity—470 Pa-s), was added to thepressure-sensitive adhesive component. Examples 9, 10, 11 and 12 wereprepared in the same manner as Example 1 except that a differentthermoplastic material component, ELVAX™ 260 (ethylene vinyl-acetatecopolymer, shear viscosity—600 Pa-s), was added to thepressure-sensitive adhesive component at ratios of pressure-sensitiveadhesive component to thermoplastic material component of 95:5, 85:15,70:30 and 40:60, respectively. Examples 13, 14 and 15 were prepared inthe same manner as Examples 3, 4 and 5, respectively, except that adifferent thermoplastic material component, ELVAX™ 660 (ethylenevinyl-acetate copolymer, shear viscosity—730 Pa-s) was added to thepressure-sensitive adhesive component. Examples 16 and 17 were preparedin the same manner as Examples 3 and 4 respectively, except that adifferent thermoplastic material component, SURLYN™ 1702(ethylene-methacrylic acid copolymer, available from DuPont) was addedto the pressure-sensitive adhesive component. Comparative Example C1 wasprepared as in Example 1 except only the pressure-sensitive adhesivecomponent, with no thermoplastic material component, was used to preparethe pressure-sensitive adhesive tape.

The viscosity ratio of the discontinuous to substantially continuouscomponent and the thickness of adhesive on samples of eachpressure-sensitive adhesive tape were determined and the 180° peeladhesion test on glass, the 180° peel adhesion test on biaxiallyoriented polypropylene (BOPP) and the shear strength were carried out inboth the down-web (DW) and cross-web (CW) directions. The results areset forth in Table 1.

TABLE 1 Peel Adhesion Peel Adhesion Glass in BOPP in Shear StrengthViscosity DW/CW DW/CW in DW/CW Example Ratio (N/dm) (N/dm) (min) C1 —39/48 33/32 230/190  1 1:15 43/42 24/32 210/230  2 1:15 62/68 27/30230/390  3 1.4:1 46/49 27/28 240/270  4 1.4:1 70/65 17/31 370/420  51.4:1 70/61 22/29 170/650  6 3.1:1 49/54 29/33 220/150  7 3.1:1 11/6528/40 300/240  8 3.1:1 1/40 7/33 190/130  9 4:1 47/50 24/33 210/290 104:1 46/52 25/36 220/310 11 4:1 20/59 20/23 640/760 12 4:1 5/11 2/3120/40 13 4.9:1 39/49 30/35 270/200 14 4.9:1 29/58 25/30 200/220 154.9:1 6/47 10/21 190/160 16 — 28/38 27/15 150/220 17 — 56/44 23/29430/340

Examples C1 through 17 exhibited the fibrillose to schistose morphologyas determined by the laser light scattering test. As can be seen fromthe data in Table 1, the addition of the thermoplastic materialcomponents (ethylene vinyl-acetate copolymers and ethylene methacrylicacid copolymers) to the acrylic pressure-sensitive adhesive componentincreased the peel adhesion to glass and/or biaxially orientedpolypropylene, and the shear strength of the control adhesive (C1) forExamples 1-4, 8, 9, 12 and 16. A concurrent increase of peel adhesionand shear strength is unusual since most rubber/resin pressure-sensitiveadhesives have a trade-off between these two properties. The enhancedproperties begin to be present at around 5% thermoplastic materialcomponent concentration. The peel adhesion enhancement is mostpronounced for the examples containing ethylene vinyl-acetatecopolymers. The shear strength was most pronounced for the examplescontaining ethylene methacrylic acid copolymers. Examples 5-7, 10-11 and13-15 demonstrate that a significant anistropic peel adhesion can beobtained with cross-web peel adhesion significantly greater than thedown-web peel adhesion.

Examples 18-22

Examples 18 and 19 and 20 were made according to Examples 3 and 4 and 5,respectively, except that a different thermoplastic material component,TENITE™ 1550P (a low-density polyethylene, shear viscosity—675 Pa-s,available from Eastman Kodak) was added to the pressure-sensitiveadhesive component. Examples 21 and 22 were made according to Examples 1and 2, respectively, except that a different thermoplastic materialcomponent, DOWLEX™ TM 2517 (a linear low-density polyethylene, shearviscosity—280 Pa-s, available from Dow Chemical) was added to thepressure-sensitive adhesive component.

The viscosity ratio of the discontinuous to substantially continuouscomponent and the thickness of adhesive on samples of eachpressure-sensitive adhesive tape were determined and the 180° peeladhesion test on glass, the 180° peel adhesion test on biaxiallyoriented polypropylene (BOPP) and the shear strength were carried out inboth the down-web (DW) and cross-web (CW) directions. The results areset forth in Table 2 together with those of Comparative Example C1.

TABLE 2 Peel Adhesion Peel Adhesion Glass in BOPP in Shear StrengthViscosity DW/CW DW/CW in DW/CW Example Ratio (N/dm) (N/dm) (min) C1 —36/43 30/29 230/190 18 4.5:1 47/45 29/33 200/210 19 4.5:1 37/59 24/38180/80 20 4.5:1 9/23 5/20 10/50 21 1.9:1 24/49 31/38 270/350 22 1.9:191/82 35/42 340/320

Examples 18-22 exhibited the fibrillous morphology as determined by thelight scattering test. As can be seen by the data in Table 2, theaddition of the low-density and linear low-density polyethylenethermoplastic material component to the acrylic pressure-sensitiveadhesive increased the peel adhesion to glass and/or biaxially orientedpolypropylene and/or the shear strength of the control adhesive (C1) forExamples 19, 21 and 22. Examples 20-21 exhibited anisotropic behaviorfor all three properties.

Examples 23-29 and Comparative Examples C2

Examples 23-29 were made according to Example 1 except that a differentpressure-sensitive adhesive layer thickness, different thermoplasticmaterial components and various ratios of pressure-sensitive adhesivecomponent to thermoplastic material component were used. In Examples23-29 and Comparative Example C2, the pressure-sensitive adhesive layerthickness was approximately 90 μm. In Examples 23 and 24, thethermoplastic material component was FINA™ 3374× (a polypropylene, shearviscosity—700 Pa-s, available from Fina Oil and Chemical) was added tothe pressure-sensitive adhesive component at ratios of 90:10 and 85:15,respectively. Examples 25 and 26 were made according to Examples 23 and24, respectively, except that the thermoplastic material component wasESCORENE™ 3860 (a polypropylene, available from EXXON). Example 27 usedDURAFLEX™ 0200 (a polybutylene, shear viscosity—682 Pa-s, available fromShell Chemical) and the ratio was 85:15.Examples 28 and 29 usedPRIMACORE™ 1430 ethylene acrylic ester copolymer, shear viscosity—630Pa-s, available from Dow Chemical) and the ratios were 92:8 and 87:13,respectively. Comparative Example C2 was made with only thepressure-sensitive adhesive component in the pressure-sensitive adhesivecomposition layer.

The viscosity ratio of the discontinuous to substantially continuouscomponent of each pressure-sensitive adhesive tape were determined andthe 180° peel adhesion test on glass, the 180° peel adhesion test onbiaxially oriented polypropylene (BOPP) and the shear strength werecarried out in both the down-web (DW) and cross-web (CW) directions. Theresults are set forth in Table 3 together with those of ComparativeExample C2.

TABLE 3 Peel Adhesion Peel Adhesion Glass in BOPP in Shear StrengthViscosity DW/CW DW/CW in DW/CW Example Ratio (N/dm) (N/dm) (min) C2 —52/50 39/37 100/130 23 4.7:1 64/59 39/38 110/180 24 4.7:1 56/56 30/34150/240 25 — 69/74 50/40 80/150 26 — 62/58 40/46 250/280 27 4.5:1 68/6636/42 130/180 28 4.2:1 68/68 34/32 120/150 29 4.2:1 62/55 33/40 110/150

Examples 23-29 exhibited the fibrillous morphology as determined by thelight scattering test. As can be seen by the data in Table 3, theaddition of various polypropylene thermoplastic material components tothe acrylic pressure-sensitive adhesive increased the peel adhesion toglass and/or biaxially oriented polypropylene and/or the shear strengthof the control adhesive (C2) for Examples 23-29. Examples 23-27 and 29exhibited anisotropic behavior for one or more of the three properties.

Examples 30-33

Examples 30-33 were made according to Example 1 except that thetemperature of zone 4 was 204° C. (400° F.), a different thermoplasticmaterial components were used and the ratio of pressure-sensitiveadhesive component to thermoplastic material component was 85:15.InExamples 30 and 31, the thermoplastic material component was Kodar™ 6763(an amorphous polyester, shear viscosity—3150 Pa-s, available fromEastman Chemical Products) and Styron™ 615 (a polystyrene, shearviscosity—650 Pa-s, available from Dow Chemical), respectively. InExamples 32 and 33, the thermoplastic material component was Plexiglas™VM100 (a polymethylmethacrylate, shear viscosity—1900 Pa-s, availablefrom Ato Haas) and PETROTHENE™ 3150B (a high density polyethylene, shearviscosity—340 Pa-s, available from Quantum Chemical), respectively. Thepressure-sensitive adhesive layer thickness was 64 μm (2.5 mils).

The viscosity ratio of the discontinuous to substantially continuouscomponent the 180° peel adhesion test on glass, the 180° peel adhesiontest on biaxially oriented polypropylene (BOPP) and the shear strengthwere carried out in both the down-web (DW) and cross-web (CW)directions. The results are set forth in Table 4 together with those ofComparative Example C1.

TABLE 4 Peel Adhesion Peel Adhesion Glass in BOPP in Shear StrengthViscosity DW/CW DW/CW in DW/CW Example Ratio (N/dm) (N/dm) (min) C1 —39/48 33/32 230/190 30 21:1 21/50 33/45 70/90 31 4.3:1 9/46 3/40 90/14032 13:1 39/39 41/38 60/90 33 2.3:1 69/64 43/40 90/140

Examples 30-33 exhibited the fibrillous morphology as determined by thelight scattering test. As can be seen by the data in Table 4, theaddition of various other thermoplastic material components to theacrylic pressure-sensitive adhesive resulted in anisotropic peeladhesion to glass and/or biaxially oriented polypropylene and/oranisotropic shear strength.

The pressure-sensitive adhesive layers of Examples 30-33 and ComparativeExample C1 were also tested for tensile and elongation properties usingthe tensile and elongation test. FIG. 1 depicts the stress-stain curvefor the down-web (DW) and cross-web (CW) directions of Example 31. Thecorresponding yield stresses for the down-web direction of Examples30-33 were 3.5 Mpa (550 PSI), 20.7 Mpa (3000 PSI), 2.2 Mpa (317 PSI) and6.3 Mpa (915 PSI), respectively. The cross-web direction of Examples30-33 did not have a yield stress but were elastomeric in nature. Thebreak elongation for Comparative Example C1 and Example 30-33 in thedown-web direction was 1143%, 1125%, 650%, 962% and 911%, respectively.The break elongation for Comparative Example C1 and Examples 30-33 inthe cross-web direction was 845%, 1638%, 1775%, 1970% and 1797%,respectively.

As the stiffer thermoplastic polymers were added to the acrylicpressure-sensitive adhesive, the down-web direction stress substantiallyincreased, the down-web direction break elongation decreased while thecross-web direction break elongation increased. This leads to cleanerbreaking of the pressure-sensitive adhesive when used alone as atransfer adhesive tape.

Examples 34-35 and Comparative Examples C3-C4

Examples 34-5 were made according to Example 33 except that a differentpressure-sensitive adhesive component and a different thermoplasticmaterial component were used. In Example 34 the pressure-sensitiveadhesive was similar to that in Example 33 except 0.3 parts ofacryloxybenzophenone, and the thermoplastic material was ELVAX™ 260. InExample 35, the pressure-sensitive adhesive was HRJ™ 4326 (2-ethyl hexylacrylate, shear viscosity 10 Pa-s, available from SchenectedyInternational) and the thermoplastic material was ELVAX™ 240.Pressure-sensitive adhesive tapes of Comparative Examples C3 and C4 weremade as in Examples 34 and 35, except they had no thermoplastic materialcomponent.

The viscosity ratio of the discontinuous to substantially continuouscomponent of each pressure-sensitive adhesive tape were determined andthe 180° peel adhesion test on glass, the 180° peel adhesion test onbiaxially oriented polypropylene (BOPP) and the shear strength werecarried out in both the down-web (DW) and cross-web (CW) directions. Theresults are set forth in Table 5.

TABLE 5 Peel Adhesion Peel Adhesion Glass in BOPP in Shear StrengthViscosity DW/CW DW/CW in DW/CW Example Ratio (N/dm) (N/dm) (min) C3 —51/50 44/43 80/90 34 4:1 64/73 45/41 100/150 C4 — 61/59 42/43 8580/656035 1:21 46/83 43/32 5640/5890

Examples 34-35 exhibited the fibrillous morphology as determined by thelight scattering test. As can be seen by the data in Table 5, theaddition of thermoplastic material components to the different acrylicpressure-sensitive adhesives resulted in anisotropic peel adhesion toglass for Example 35 and enhanced peel from glass for Example 34.

Examples 36-42 and Comparative Examples C5-C6

Examples 36-42 were made according to Example 1 except that a differentpressure-sensitive adhesive and a different thermoplastic materialcomponent were used at various ratios of pressure-sensitive adhesivecomponent to thermoplastic material component, and the thickness of thepressure-sensitive adhesive composition varied. In addition, thepressure-sensitive adhesive of some of the Examples contained atackifying material. The pressure-sensitive adhesive used in Examples36-42 and Comparative Examples C5-C6 was a suspension polymerizedacrylic pressure-sensitive adhesive instead of the water emulsionpolymerized adhesive used in Example 1. The suspension polymerizedacrylic pressure-sensitive adhesive was prepared in accordance with U.S.Pat. No. 4,833,179 (Young et al.) in the following manner: A two litersplit reactor equipped with condenser, thermowell, nitrogen inlet,stainless steel motor-driven agitator, and a heating mantle withtemperature control was charged with 750 g deionized water, to which wasadded 2.5 g of zinc oxide and 0.75 g hydrophilic silica (CAB-O-SIL™EH-5, available from Cabot Corp.) and was heated to 55° C. while purgingwith nitrogen until the zinc oxide and silica were thoroughly dispersed.At this point, a charge of 480 g isooctyl acrylate, 20 g methacrylicacid, 2.5 g initiator (VAZO™ 64, available from DuPont Co.) and 0.5 gisooctyl thioglycolate chain transfer agent were mixed together. Theresulting solution with initiator and chain transfer agent was thenadded to the initial aqueous mixture while vigorous agitation (700 rpm)was maintained to obtain a good suspension. The reaction was continuedwith nitrogen purging for at least 6 hours, during which time thereaction was monitored to maintain a reaction temperature of less than70° C. The resulting pressure-sensitive adhesive was collected and driedto at least 90% solids by weight. In Examples 36-39 the thermoplasticmaterial component was Styron™ 615 and the ratio of thepressure-sensitive adhesive to thermoplastic material was 95:5, 90:10,90:10 and 80:20, respectively. The pressure-sensitive adhesive tapes ofExamples 40-42 were made according to Example 36, respectively, exceptthe pressure-sensitive adhesive further contained an aliphatic/aromaticC9 tackifying material, ESCOREZ™ 2393 (available from EXXON) in a ratioof pressure-sensitive adhesive to tackifying material or 76:19, 76:19and 64:16, respectively, and the thickness of the pressure-sensitiveadhesive composition was approximately 46 μm, 30 μm and 33 μm,respectively. Comparative Examples C5 and C6 were made according toExample 36 except with only the pressure-sensitive adhesive component inthe pressure-sensitive adhesive composition.

The thickness of adhesive on samples of each pressure-sensitive adhesivetape, the 180° peel adhesion test on glass, the 180° peel adhesion teston biaxially oriented polypropylene (BOPP) and the shear strength werecarried out in both the down-web (DW) and cross-web (CW) directions. Theresults are set forth in Table 6.

TABLE 6 Peel Adhesion Peel Adhesion Glass in BOPP in Shear StrengthThickness DW/CW DW/CW in DW/CW Example (μm) (N/dm) (N/dm) (min) C5 4646/42 24/26 120/200 C6 33 45/40 23/23 180/210 36 46 55/52 6/24 340/46037 46 22/56 6/29 290/390 38 28 21/54 2/24 240/390 39 46 3/51 2/19410/600 40 46 75/75 11/17 370/420 41 30 58/71 10/14 440/700 42 33 44/6336/62 360/430

Examples 36-42 exhibited the fibrillous morphology as determined by thelaser light scattering test. As can be seen by the data in Table 6, theaddition of thermoplastic material components to the different acrylicpressure-sensitive adhesives resulted in anisotropic peel adhesion toglass and/or biaxially oriented polypropylene and anisotropic shearstrength. The pressure-sensitive adhesive properties were notsignificantly dependent on thickness over the range tested as seen byComparative Examples C5 and C6. The addition of a tackifying material tothe pressure-sensitive adhesive component shifted the peel adhesionvalues higher and decreased the anisotropic behavior.

Examples 43-46 and Comparative Examples C7-C9

A compounding and coating apparatus for making synthetic and naturalrubber pressure-sensitive adhesives is described in U.S. Pat. No.5,539,033, which is incorporated herein by reference. In Examples 43-44,a synthetic rubber, NATSYN™ 2210 (synthetic polyisoprene, shearviscosity—1500 Pa-s, available from Goodyear), a tackifier, EXCOREZ™1310LC and a plasticizer, mineral oil, and a thermoplastic materialcomponent, Styron™ 615 were melt blended in a 30 mm diameter fullyintermeshing co-rotating twin screw extruder (Model ZSK 30, availablefrom Werner-Pfleiderer, having a length to diameter ratio of 47:1). Boththe elastomeric and thermoplastic polymers were fed into zone 1(barrel 1) of the extruder. The tackifier was split-fed into zone 2(barrel 6-10%) and zone 3 (barrel 8-90%). The plasticizer were fed intobarrel 10. The temperature progressively increased from 60° C. to 204°C. from zone 1 to zone 5.The temperature of the remaining zones wasmaintained at 170° C. (350° F.). The screw speed was 200 revolutions perminute. The feed rates were adjusted to provide a pressure-sensitiveadhesive component with a ratio of synthetic rubber to tackifier toplasticizer of 61:32:7 and a pressure-sensitive adhesive compositionwith a ratio of pressure-sensitive adhesive component to thermoplasticmaterial component of 90:10 and 80:20 for Examples 43 and 44,respectively.

The blend was extruded onto 51 μm (2 mil) thick biaxially orientedpolyethylene terephthalate film using a contact die with a rotating rodto form a pressure-sensitive adhesive tape having a pressure-sensitiveadhesive layer thickness of 38 μm. The film was moving at 9 m/min (30fpm). Example 45-46 were made according to Examples 43-44, respectively,except a natural rubber, (CV-60) was used in place of the syntheticrubber. Comparative Examples C7-C9 were made according to Examples 43and 45, respectively, except no thermoplastic material component wasadded. Comparative Example C8 is Example 44 dissolved in toluene andcoated onto 51 μM (2 mil) PET film.

The thickness of adhesive on samples of each pressure-sensitive adhesivetape were determined, and the 180° peel adhesion test on glass, the 180°peel adhesion test on biaxially oriented polypropylene (BOPP) and theshear strength were carried out in both the down-web (DW) and cross-web(CW) directions.

The results are set forth in Table 7.

TABLE 7 Peel Adhesion Peel Adhesion Glass in BOPP in Shear StrengthDW/CW DW/CW in DW/CW Example (N/dm) (N/dm) (min) C7 26/21 34/35 50/50 439/18 20/26 60/40 44 1/20 7/28 200/800 C9 7/4 13/14 480/500 45 0/11 11/20420/620 46 0/8 4/20 1300/1400 C8 18/20 — 60/70

Examples 43-46 exhibited the fibrillous morphology as determined by thelaser light scattering test and is depicted in FIGS. 5 and 10 forExample 44 and Example 46, respectively. This was also confirmed bycryo-fracture SEM analysis of osmium tetroxide stained samples and isdepicted in FIGS. 3-4, and 8-9 for Example 44 and Example 46,respectively. As can be seen by the data in Table 7, the addition ofthermoplastic material components to either natural or synthetic rubberpressure-sensitive adhesives resulted in anisotropic peel adhesion toglass and biaxially oriented polypropylene. In addition, anisotropicshear strength was also observed. FIGS. 6 and 7 depict the sphericalmorphology for Comparative Example C8. This spherical morphologyexhibits lower shear strength and isotropic peel adhesion as compared tothe compositions of the invention.

Examples 47-50 and Comparative Examples C10-C11

Examples 47-50 and Comparative Examples C10-C11 were made according toExamples 43-46 and Comparative Examples C7 and C9, respectively, exceptthey were subsequently exposed to electron beam radiation. Samples ofeach tape were subjected to electron beam radiation using anELECTROCURTAIN™ Model CB-175 (available from Energy SciencesIncorporated, Wilmington, Mass.) at a 125 kV accelerating voltage. Theirradiation was performed in an inert nitrogen atmosphere at acalculated dose of 4.0 Mrads.

The 180° peel adhesion test on glass, the 180° peel adhesion test onbiaxially oriented polypropylene (BOPP) and the shear strength werecarried out in both the down-web (DW) and cross-web (CW) directions. Theresults are set forth in Table 7.

TABLE 8 Peel Adhesion Peel Adhesion Glass in BOPP in Shear StrengthDW/CW DW/CW in DW/CW Example (N/dm) (N/dm) (min) C10 21/20 23/266580/3870 47 12/21 16/28 2370/2860 48 2/16 5/23 2040/4470 C11 4/3 15/164060/4890 49 1/13 5/20 3390/4500 50 0/3 1/13 3170/3140

Examples 47-50 still exhibited the fibrillous morphology as determinedby the laser light scattering test. This was also confirmed bycryo-fracture SEM analysis of osmium tetroxide stained samples. As canbe seen by the data in Table 8, subsequent crosslinking generally raisedshear strengths and decreased peel adhesions but did not significantlychange the anisotropic properties.

Example 51 and Comparative Example C12

In Example 51 and Comparative Example C12, pressure-sensitive adhesivetapes were prepared as in Example 37 and Comparative Example C5, exceptthe pressure-sensitive adhesive layer thickness was 58 μm and adifferent substrate was used. The substrate was a non-occlusive, i.e.breathable, woven backing which has an 180×48 plain weave acetatetaffeta cloth, 75 denier fiber in the warp direction and 150 denierfiber in the weft direction, available from Milliken and Co.,Spartanburg, Ga.

The pressure-sensitive adhesive tapes were tested in both the DW and CWdirection for skin adhesion immediately after application, T₀, and after48 hours, T₄₈, skin adhesion lift after 48 hours and skin adhesionresidue after 48 hours.

The results are set forth in Table 9.

TABLE 9 Comparative Example 51 Example C12 T₀ — DW (N/dm) 25 81 T₀ — CW(N/dm) 43 74 T₄₈ — DW (N/dm) 149 265 T₄₈ — CW (N/dm) 199 264 T₄₈ Lift —DW 0.1 0.1 T₄₈ Lift — CW 0.1 0.4 T₄₈ Residue — DW 0.6 1.1 T₄₈ Residue —CW 0.6 1.1

As can be seen from the data in Table 9, the pressure-sensitive adhesivetapes of Example 51 had anisotropic peel performance from skin for theT₀:T₄₈ adhesion and can be controlled by appropriate blending of theacrylic adhesive component and the thermoplastic component. Thus thetape is easy to remove from skin when pulled in one direction but hasgood holding power.

Examples 52-57 and Comparative Examples C13-C14

The adhesives of the invention can control the rate of drug release froma multilayer transdermal drug delivery device as the procedure describedbelow demonstrates. The rate control adhesives used in test patches ofExamples 52-57 and Comparative Examples C13-C14 were made according toExamples 30, 32, 33, 34, 37, and 42 and Comparative Examples C13-C14,respectively, except each adhesive was applied to a release paper.

Each test patch consisted of 4 layers: a backing, a first adhesive layercontaining drug, a second adhesive layer to provide rate control, and arelease liner. Acrylate adhesive copolymer (57.5/39/3.5 w/w/w isooctylacrylate/2-hydroxyethyl acrylate/ELVACITE™ (ICI Acrylics) 1020polymethylmethacrylate macromonomer 50% solids in ethyl acetate) andphenobarbitol were combined then mixed to provide a homogeneous coatingformulation. The formulation was coated onto a backing (1109 SCOTCHPAK™tan, polyester film laminate, available from 3M Company) then dried at43° C. for 15 minutes. The resulting coating contained 5 percent byweight of phenobarbital and had a thickness of 5 mils (127 μm). Theexposed surface was laminated to a layer of rate control adhesive of theinvention carried on a release liner. Test patches (round, 5 cm²) weredie cut from the resulting laminate.

To prevent release of the drug from the periphery of the patch, eachtest patch was concentrically aligned with an adhesive overlay. Anadhesive overlay (round, 25 cm², 1, mil (25 μm) layer of polyisobutylenecoated onto a backing) was laminated to the backing of the test patchsuch that the patch and the overlay were concentrically aligned. Therelease liner was removed from the test patch. A ring-shaped overlay (25cm², with an inner diameter of 22 mm, 1 mil (25 μm) layer ofpolyisobutylene coated onto a backing) was centered over the testpatch/overlay laminate, then the adhesive surfaces were laminatedtogether to provide a seal around the periphery of the test patch. Therelease liner was placed back on the test patch, then the entireassembly was die cut (round 12.5 cm²) so that the test patch wascentered. The assembly was heat sealed in a foil pouch and allowed toequilibrate for 8 days.

The assembly was then removed from the pouch and affixed to one end of aglass plate with double coated tape, so the backing of the assembly wasin direct contact with the double coated tape. The release liner wasremoved from the test patch. The glass slide was suspended in a 120 mltall form glass jar equipped with a magnetic stirrer. A release solutionwas prepared by combining 6 L of HPLC grade water; 2.2835 g of sodiumphosphate, monobasic monohydrate; 9.7538 g of sodium phosphate, dibasicheptahydrate; and 46.4502 g sodium chloride. A 100 ml portion of 32° C.release solution was added to the jar. The test patch was completelysubmerged in the release solution. The jar was capped, then placed in atemperature controlled chamber at 32° C. The release solution wasstirred throughout the experiment.

At specificed time points (1 hr, 6.5 hr, 24 hr, 72 hr, 168 hr and 336hr), the cap was removed and a 1.0 mL sample of release solution wasremoved and placed in a HPLC sample vial. The phenobarbitol content ofthe sample was quantitated using reverse-phase high performance liquidchromatography (Waters LC1 Module Plus; column: 15 cm×4.6 mm innerdiameter Supelcosil LC-ABZ, 5 μm particle size; mobile phase: 75% 25 mMpotassium phosphate monobasic buffer/25% acetonitrile v/v; flow rate:2.0, ml/min; detector: uv, 254 , nm at 0.005 AUFS; run time: 10 minutes;injection volume 20 μL).

The percent released was obtained using the following equation:$R_{i} = {\frac{\lbrack {{C_{i} \times ( {100 - ( {I - 1} )} \rbrack} + {\sum\limits_{a = 1}^{i}\quad C_{a - 1}}} \rbrack}{( {{T.C.} \times {S.A.}} )} \times 100}$

where:

R_(i)=percent of phenobarbitol released from the sample a time point “i”

i=sequential number of time point (values: 1, 2, 3 . . . n)

C_(i)=sample concentration (μg/mL) HPLC analysis at time point I

C₀=0

T.C.=theoretical phenobarbitol content in μg/cm²

S.A.=surface area of test patch in cm²

The table below shows the thickness of the rate control adhesive and thecumulative percent released at each time point. Each value is theaverage of determinations for four separate test patches.

TABLE 10 Release Rate of Phenobarbitol in Percent Example Thickness 1 hr6.5 hr 24 hr 72 hr 168 hr 336 hr 52 63.5 3 13 36 77 96 100 53 63.5 4 1236 76 95 100 54 63.5 3 9 29 66 91 99 55 127 3 9 21 51 83 97 C13 63.5 415 41 81 97 100 56 45.7 3 9 29 63 90 99 57 45.7 1 5 13 33 61 84 C14 45.74 11 36 73 93 100

The rate of diffusion of a drug can be varied by the addition of anothersubstantially immiscible thermoplastic material component to apressure-sensitive adhesive where the minor component forms discretedomains that have a fibrillous to schistose morphology. This augmentsthe differential adsorption and desorption effects of two polymericdomains with a torturous path caused during the formation of the ratecontrolling adhesive layer.

Example 58 and Comparative Examples C15-C17

The adhesives of the invention that contain thermoplastic elastomericcomponents can control the rate of drug release from a multilayertransdermal drug selivery device as the procedure below demonstrates. InExample 58, the water suspension polymerizd acrylic pressure-sensitiveadhesive component described in Example 36 was melt blended with athermoplastic elastomeric adhesive component (prepared by blending 50parts thermoplastic elastomeric block copolymer KRATON™ D1107P, 1 partantioxidant IRGANOX™ 1010 and 50 parts tackifying resin ESCOREZ™ 1310LC)in a corotating twin screw extruder, Model ZSK 30, having 30 mm diameterbarrel and a length to diameter ratio of 37:1 with the acrylic adhesiveto thermoplastic elastomer adhesive ratio being 50:50, respectively. Thethermoplastic elastomer block copolymer was fed into zone 1, thetackifying resin in zone 2 and the acrylic pressure-sensitive adhesivein zone 3. Temperatures were maintained between 249° C. and 165° C. Theresulting pressure-sensitive adhesive composition was applied to releasepapers such that the adhesive layer was 51 μm thick.

In Comparative Example C15, the pressure-sensitive adhesive was preparedusing only the acrylic adhesive of Example 58. In Comparative ExampleC16, the pressure-sensitive adhesive was prepared as follows. Acrylateadhesive in example 36 was dissolved in a 90/10 heptane/isopropylalcohol mixture at 20% solids. The thermoplastic elastomer Kraton™ 1107and tackifier ESCOREZ™ 1310LC at a 50/50 mix were dissolved in tolueneat 50% solids.

The 50/50 ratio of acrylate/tacified thermoplastic elastomer wasprepared by combining the appropriate amounts of acrylate adhesive andkraton adhesive blend.

The pressure-sensitive composition in solvent was knife coated anddried. The dried coating thickness was 51 μm (2 mil). The dryingconditions were 5 minutes at 43° C. (110° F.), 2 minutes at 85° C. (185°F) and 2 minutes at 107° (225° F.).

In Comparative Example C17, the pressure-sensitive adhesive was preparedusing only the tackified thermoplastic elastomer component of Example58.

Each test patch consisted of 4 layers: a backing, a first adhesive layercontaining drug, a second adhesive layer to provide rate control, and arelease liner. Acrylate adhesive copolymer (59/39/2 w/w/w isooctylacrylate/2-hydroxyethyl acrylate/ELVACITE™ (ICI Acrylics) 1020polymethylmethacrylate macromonomer 51.9% solids in 95/5 ethylacetate/isopropanol) and phenobarbital were combined then mixed toprovide a homogeneous coating formulation. The formulation was coatedonto a backing (1109 SCOTCHPAK™ tan, polyester film laminate, availablefrom 3M Company) then dried at 43° C. for 15 minutes. The resultingcoating contained 8 percent by weight of phenobarbital and had athickness of 15 mils (382 μm). The exposed surface was laminated to a 2mil (51 μm) layer of rate control adhesive carried on a release liner.Test patches (round, 5 cm²) were die cut from the resulting laminate.

To prevent release of the drug from the edge of the patch, each testpatch was fitted with an adhesive overlay. An adhesive overlay (round,25 cm², 1 mil (25 μm) layer of polyisobutylene coated onto a backing)was laminated to the backing of the test patch such that the patch andthe overlay were concentrically aligned. The release liner was removedfrom the test patch. A ring-shaped overlay (25 cm², with an innerdiameter of 22 mm, 1 mil (25 μm) layer of polyisobutylene coated onto abacking) was centered over the test patch/overlay laminate, then theadhesive surfaces were laminated together to provide a seal around theperiphery of the test patch. The release liner was placed back on thetest patch, then the entire assembly was die cut (round 12.5 cm²) sothat the test patch was centered. The assembly was heat sealed in a foilpouch and allowed to equilibrate for 8 days.

The assembly was then removed from the pouch and affixed to one end of aglass plate with double coated tape, so that backing of the assembly wasin direct contact with the double coated tape. The release liner wasremoved from the test patch. The glass slide was suspended in a 120 mltall form glass jar equipped with a magnetic stirrer. A release solutionwas prepared by combining 61 of HPLC grade water; 2.2835 g of sodiumphosphate, monobasic monohydrate; 9.7538 g of sodium phosphate, dibasicheptahydrate; and 46.4502 g sodium chloride. A 100 mL potion of 32° C.release solution was added to the jar. The test patch was completelysubmerged in the release solution. The jar was capped, then placed in atemperature controlled chamber at 32° C. The release solution wasstirred throughout the experiment.

At specified time points (1 hr, 4 hr, 8 hr, 24 hr, 97.5 hr, 168 hr, 264hr and 336 hr), the cap was removed and a 1.0 ml sample of releasesolution was removed and placed in a HPLC sample vial. The phenobarbitalcontent of the sample was quantitated using reverse-phase highperformance liquid chromatography (Waters LC1 Module Plus; column: 15cm×4.6, mm inner diameter Supelcosil LC-ABZ, 5 μm particle size; mobilephase: 75% 25 mM potassium phosphate monobasic buffer/25% acetonitrilev/v; flow rate: 2.0 ml/min; detector: uv, 254 nm at 0.005 AUFS; runtime: 10 minutes, injection volume 20 μl).

The percent released was obtained using the following equation:$R_{i} = {\frac{\lbrack {{C_{i} \times ( {100 - ( {I - 1} )} \rbrack} + {\sum\limits_{a = 1}^{i}\quad C_{a - 1}}} \rbrack}{( {{T.C.} \times {S.A.}} )} \times 100}$

where:

R_(i)=percent of phenobarbital released from the sample a time point “i”

i=sequential number of time point (values: 1, 2, 3 . . . n)

C_(i)=sample concentration (μg/ml) HPLC analysis at time point I

C₀=0

T.C.=theoretical phenobarbital content in μg/cm²

S.A.=surface area of test patch in cm²

The table below shows the identity of the adhesive used in the ratecontrol layer and the cumulative percent released at each time point.Each value is the average of determinations for four separate testpatches.

TABLE 11 Release Rate of Phenobarbitol in Percent 1 8 24 49 97.5 168 264336 Example hr hr hr hr hr hr hr hr C15 1 3 9 16 27 41 56 64 58 0 0 1 12 4 6 7 C16 0 1 2 3 6 11 18 22 C17 0 0 0 0 1 1 2 2

The rate of diffusion of a drug can be varied by the addition of anothersubstantially immiscible thermoplastic material component to apressure-sensitive adhesive where the minor component forms discretedomains that have a fibrillous to schistose morphology. As seen bycomparing Example 58 to Comparative Example C16, the fibrillous toschistose morphology augments the differential adsorption and desorptioneffects of two polymeric domains with a torturous path caused during theformation of the rate controlling adhesive layer.

Example 60

In Example 60, a pressure-sensitive adhesive component as described inExample 36 was melt-blended in a 30 mm diameter fully intermeshingco-rotating twin screw extruder (Model ZSK-30, available from Werner &Pfleiderer Corp., Ramsey, N.J., having a length to diameter ratio of36:1) with a process similar to that described in Example 19 of U.S.Pat. No. 5,539,033.The screw configuration used was the same as shown inFIG. 4 of U.S. Pat. No. 5,539,033.The elastomeric polymer, NATSYN™ 2210was added in zone 1.The acrylic pressure-sensitive adhesive was added inzone 9.The elastomer to acrylic pressure-sensitive adhesive ratio was50:50. The screw speed was 475 rpm. Air was injected into zone 3 and thetemperature was maintained at 133° C. to reduce the molecular weight ofthe elastomer in order to make it more hot melt processable. The dietemperature was 154° C. The pressure-sensitive adhesive was applied as a42 μm thick layer onto a 30 μm thick polyethylene terephthalate filmmoving at 9.1 m/min. The pressure-sensitive adhesive layer wasessentially non-grainy, tacky to the touch, and exhibited the fibrillousmorphology as determined by the light scattering test.

The various modifications and alterations of this invention will beapparent to those skilled in the art without departing from the scopeand spirit of this invention and this invention should not be restrictedto that set forth herein for illustrative purposes only.

What is claimed is:
 1. A pressure-sensitive adhesive layer comprising ablend of at least one pressure-sensitive adhesive component and at leastone thermoplastic, elastomeric, tackified elastomeric, or thermoplasticelastomeric material component being immiscible with thepressure-sensitive adhesive component at room temperature, said layerhaving an anisotropic morphology comprising two axes perpendicular toeach other, both parallel to the main surface layer, said axescomprising a longitudinal axis in the down-web direction and atransverse axis in the cross-web direction, said morphology furthercomprising at least two distinct domains, a first substantiallycontinuous domain comprising the at least one pressure sensitiveadhesive component and a second domain comprising the at least onethermoplastic, elastomeric, tackified elastomeric, or thermoplasticelastomeric material component being fibrillose to schistose in natureand oriented along the down-web direction.
 2. The pressure-sensitiveadhesive layer of claim 1 having at least one pressure-sensitiveadhesive property from the group consisting of (a) a peel adhesiongreater than and shear strength similar to that of thepressure-sensitive adhesive component if used alone, (2) a shearstrength greater than and peel adhesion similar to that of thepressure-sensitive adhesive component if used alone, (3) an anisotropicpeel adhesion, (4) an anisotropic shear strength and (5) a tensilestress in the down-web direction that is at least two times greater thanthe tensile stress in the cross-web direction for all elongations up tothe break elongation.
 3. The pressure-sensitive adhesive layer of claim1 wherein the pressure-sensitive adhesive component is selected from thegroup consisting of acrylic, styrene block copolymer, natural rubber,synthetic rubber, silicone urea polymer, polyurethane,polyvinylmethylether and blends thereof.
 4. The pressure-sensitiveadhesive layer of claim 3 wherein the pressure-sensitive adhesivecomponent is acrylic.
 5. The pressure-sensitive adhesive layer of claim4 wherein the acrylic pressure-sensitive adhesive component comprises apolymer of a C₃-C₁₂ alkyl ester.
 6. The pressure-sensitive adhesivelayer of claim 5 wherein the acrylic pressure-sensitive adhesivecomponent comprises a polymer of isooctyl acrylate, 2-ethyl-hexylacrylate or n-butyl acrylate.
 7. The pressure-sensitive adhesive layerof claim 4 wherein the acrylic pressure-sensitive adhesive componentfurther comprises a polar component.
 8. The pressure-sensitive adhesivelayer of claim 7 wherein the polar component comprises acrylic acid,methacrylic acid, ethylene vinyl acetate, N-vinyl pyrrolidone andstyrene macromer.
 9. The pressure-sensitive adhesive layer of claim 8wherein the acrylic pressure-sensitive adhesive component comprisesabout 100 to 80 weight percent alkyl ester component and up to about 20weight percent polar component.
 10. The pressure-sensitive adhesivelayer of claim 1 wherein the pressure-sensitive adhesive component issilicone urea.
 11. The pressure-sensitive adhesive layer of claim 1wherein the pressure-sensitive adhesive component is poly-alpha-olefin.12. The pressure-sensitive adhesive layer of claim 1 wherein thepressure-sensitive adhesive component is natural rubber or syntheticrubber.
 13. The pressure-sensitive adhesive layer of claim 1 wherein thethermoplastic elastomeric materials comprise linear, radial, star,tapered or branched copolymers.
 14. The pressure-sensitive adhesivelayer of claim 1 wherein the thermoplastic elastomeric materialcomponent is selected from the group consisting of linear, radial, starand tapered styrene-isoprene block copolymers, linearstyrene-(ethylene-butylene) block copolymers, linearstyrene-(ethylene-propylene) block copolymers, styrene-isoprene-styreneblock copolymers, star styrene-butadiene block copolymers,polyetheresters, and poly-alpha-olefins.
 15. The pressure-sensitiveadhesive layer of claim 1 wherein the thermoplastic material componentis selected from the group consisting of ethylene-vinyl acetate,polyolefin, polystyrene, amorphous polyester, polymethyl methacrylate,isotactic polypropylene, linear low density polyethylene, low densitypolyethylene, high density polyethylene, polybutylene, and nylon. 16.The pressure-sensitive adhesive layer of claim 1 wherein the elastomericmaterial component is selected from the group consisting of naturalrubbers, butyl rubbers, synthetic polyisoprenes, ethylene-propylenes,polybutadienes, polyisobutylenes, and styrene-butadiene random copolymerrubbers.
 17. The pressure-sensitive adhesive layer of claim 1 furthercomprising a tackifier.
 18. The pressure-sensitive adhesive layer ofclaim 16 further comprising a tackifier selected from the groupconsisting of rosins, synthetic hydrocarbon resins, terpene resins, andliquid rubbers.
 19. The pressure-sensitive adhesive layer of claim 1comprising a thermoplastic elastomeric material component and furthercomprising a tackifying resin, said tackifying resin optionallycomprising up to 200 weight percent based on the weight percent ofthermoplastic elastomeric material.
 20. The pressure-sensitive adhesivelayer of claim 1 wherein the layer comprises 40 to 95 weight percentpressure-sensitive adhesive component and 5 to 60 weight percentthermoplastic material component.
 21. The pressure-sensitive adhesivelayer of claim 1 wherein the layer comprises 5 to 95 weight percentpressure-sensitive adhesive component and 5 to 95 weight percentelastomeric material component.
 22. The pressure-sensitive adhesivelayer of claim 1 wherein the layer comprises 40 to 95 weight percentpressure-sensitive adhesive component and 5 to 60 weight percenttackified elastomeric material component.
 23. The pressure-sensitiveadhesive layer of claim 1 wherein the layer comprises 5 to 95 weightpercent pressure-sensitive adhesive component and 5 to 95 weight percentthermoplastic elastomeric material component.
 24. The pressure-sensitiveadhesive layer of claim 1 comprising a blend of 40 to 95 weight percentof at least one pressure-sensitive adhesive component and 5 to 60 weightpercent of at least one thermoplastic material component selected fromthe group consisting of polystyrene, amorphous polyester, polymethylmethacrylate and nylon, said layer having an anisotropic peel adhesion.25. The pressure-sensitive adhesive layer of claim 24 wherein thepressure-sensitive adhesive component is selected from the groupconsisting of acrylic, styrene block copolymer, natural rubber,synthetic rubber, silicone urea polymer, polyurethane,polyvinylmethylether and blends thereof.
 26. The pressure-sensitiveadhesive layer of claim 24 wherein the pressure-sensitive adhesivecomponent is styrene block copolymer.
 27. A process for producing thepressure-sensitive adhesive layer of claim 1, comprising: (a) meltmixing said at least one pressure-sensitive adhesive component and saidat least one thermoplastic, elastomeric, tackified elastomeric, orthermoplastic elastomeric polymer component, (b) (1) forming said meltblended components into a layer under shear or extensional flowconditions or both or (2) forming and drawing said melt blendedcomponents, to form said pressure-sensitive adhesive layer, and (c)allowing said layer to cool.
 28. The process of claim 27 wherein themixing is carried out under dispersive or distributive conditions or acombination thereof.
 29. The process of claim 27 wherein the mixing iscarried using either a batch or continuous process.
 30. The process ofclaim 29 wherein the batch process is carried out using internal mixingor roll milling.
 31. The process of claim 29 wherein the continuousprocess is carried out using a single screw extruder, a twin screwextruder, a disk extruder, a reciprocating single screw extruder or apin barrel single screw extruder.
 32. A pressure-sensitive adhesive tapecomprising a substrate and on the substrate the pressure-sensitiveadhesive layer of claim
 1. 33. A pressure-sensitive adhesive tapecomprising a substrate and on the substrate the pressure-sensitiveadhesive layer of claim
 24. 34. A pressure-sensitive adhesive electricaltape comprising a polyvinyl chloride substrate or a substrate film of ablend of ethylene-vinyl acetate and ethylene-propylene-diene rubber andon the substrate, a pressure-sensitive adhesive layer comprising a blendof about 5 to 95 weight percent of an acrylic pressure-sensitiveadhesive and about 5 to 95 weight percent of a thermoplastic elastomericblock copolymer, said thermoplastic elastomeric block copolymer beingimmiscible with said pressure-sensitive adhesive, said layer having ananisotropic morphology comprising two axes perpendicular to each other,both parallel to the main surface layer, said axes comprising alongitudinal axis in the film-forming direction and a transverse axis inthe cross-web direction, said morphology further comprising at least twodistinct domains, a first substantially continuous domain comprising theat least one pressure sensitive adhesive and a second domain comprisingthe thermoplastic elastomeric block copolymer being fibrillose toschistose in nature and oriented along the film-forming direction.
 35. Adouble coated pressure-sensitive adhesive tape comprising a substrateand on at least one face of the substrate the pressure-sensitiveadhesive layer of claim 1 and on any other face of said substrate apressure-sensitive adhesive.
 36. A process for preparing apressure-sensitive adhesive tape having an pressure-sensitive adhesivelayer of claim 1, comprising: (a) melt mixing said at least onepressure-sensitive adhesive component and said at least onethermoplastic, elastomeric, tackified elastomeric, or thermoplasticelastomeric polymer component, (b) (1) extruding the melt blendedcomponents under shear or extensional flow conditions or both onto asubstrate or (2) extruding and drawing the melt blended components ontoa substrate, to form said pressure-sensitive adhesive layer on saidsubstrate, and (c) allowing said tape to cool.
 37. A process forpreparing a pressure-sensitive adhesive tape having anpressure-sensitive adhesive layer of claim 1, comprising: (a) meltmixing said at least one pressure-sensitive adhesive component and saidat least one thermoplastic, elastomeric, tackified elastomeric, orthermoplastic elastomeric polymer component to a vessel, (b) (1) formingthe melt blended components into a layer under shear or extensional flowconditions or both onto a coextruded substrate or (2) forming anddrawing the melt blended components onto a coextruded substrate, saidsubstrate optionally comprising a film forming polymeric resin, to forma coated construction comprising said pressure-sensitive adhesive, and(c) allowing said construction to cool.
 38. A process for preparing apressure-sensitive adhesive tape having an pressure-sensitive adhesivelayer of claim 1, comprising: (a) melt mixing said at least onepressure-sensitive adhesive component and said at least onethermoplastic, elastomeric, tackified elastomeric, or thermoplasticelastomeric polymer component, (b) (1) forming the melt blendedcomponents into a layer under shear or extensional flow conditions orboth or (2) forming and drawing the melt blended components, to formsaid pressure-sensitive adhesive layer(s), said adhesive layer(s) beingfed to the outer portions of a feed block having at least three layersand a film forming polymeric resin being fed to a middle portion of saidfeed block to form a double-coated pressure-sensitive tape, and (c)allowing said tape to cool.
 39. A pressure-sensitive adhesive articlecomprising the pressure-sensitive adhesive of claim 1 in a transdermaldrug delivery device.
 40. A graphic arts film comprising thepressure-sensitive adhesive of claim
 1. 41. A pressure-sensitiveadhesive article for adhesion to skin comprising a substrate and on thesubstrate the pressure-sensitive adhesive of claim
 1. 42. The article ofclaim 41 wherein said substrate is occlusive or non-occlusive.
 43. Thearticle of claim 42 wherein said occlusive backing is a film, a foammaterial, or laminate thereof.
 44. The article of claim 42 wherein saidnon-occlusive backing is a perforated polymeric film, a foam material, awoven fabric or a nonwoven fabric.